Square D QOB345 - 45 A, 240 V, 3-Pole Bolt-On Circuit Breaker | AmpState

Meet the Square D QOB345 — a 45A, 240V, 3-pole bolt-on molded case circuit breaker engineered for dependable branch circuit protection in panelboards and load centers. Built to stand up to real-world use, this breaker delivers reliable overcurrent and short‑circuit protection where it matters most.

What sets the QOB345 apart?

• Secure bolt-on mounting provides a rigid, vibration‑resistant bus connection, reducing movement and loosening in demanding environments.
• Thermal-magnetic trip unit offers stable, repeatable protection by precisely responding to overloads and short circuits, helping prevent nuisance trips while safeguarding equipment.
• OEM-compatible design is made to integrate with matching Square D load centers and panelboards, simplifying installation and serviceability.
• Versatile application suitable for residential, commercial, and light industrial settings, covering a wide range of distribution needs.
• Three-pole, 240V configuration ideal for 3-phase systems, delivering balanced protection across all phases.

• Manufacturer: Square D
• Part Number: QOB345
• Type: Thermal-magnetic molded case circuit breaker
• Amperage Rating: 45A
• Voltage Rating: 240V
• Number of Poles: 3
• Mounting Style: Bolt-on
• Application: Branch circuit overcurrent and short-circuit protection

Ideal use cases

• Upgrading aging panels or adding protection in new panel installations for residential, commercial, and light industrial projects.
• Protecting feeders and individual circuits in panelboards where dependable, consistent trip performance is crucial.
• Situations where a robust, vibration-resistant connection is needed to maintain panel integrity over time.

Why choose bolt-on over plug-on in this context? The bolt-on design provides a sturdier mechanical bond to the bus, which translates to improved stability in panels subject to vibration, easier field servicing in crowded enclosures, and long-term reliability in critical distribution paths.

Who should consider the Square D QOB345? Electricians, facilities managers, and contractors responsible for electrical distribution who require precise, durable 3-pole protection at 45A and 240V, backed by OEM compatibility and trusted Square D engineering.

When you pair the QOB345 with the appropriate OEM panelboard, you get cohesive protection that aligns with code expectations, reduces unexpected trips, and streamlines maintenance—delivering peace of mind for everyday electrical distribution needs.